Pressure cooker comprising calibrated leakage means

ABSTRACT

A household appliance for cooking under pressure, the appliance being provided with bistable calibrated leakage means suitable for taking up an open position in which the pressure inside the appliance is allowed to increase continuously to above a determined pressure P 0 , while also allowing air to be bled from the appliance, and a closed position corresponding to an absence of leakage of air to the outside, the open position being sustained until a predetermined pressure value P 1  is reached. Rather than being sustained until the predetermined pressure P 1  is reached, the open position is sustained for one of a predetermined time interval Δt after P 0  is reached, and until a predetermined temperature value T 1  is reached. The appliance is provided with at least one closure/opening safety means whose position is sensitive to pressure.

TECHNICAL FIELD

The present invention relates to the general field of householdappliances for cooking under pressure, such an appliance including abowl and a lid designed to be locked onto the bowl so as to make itpossible for the pressure inside the appliance to be increased, and forfood contained in the bowl to be cooked under pressure.

The present invention relates to a household appliance for cooking underpressure, the appliance including a cooking bowl and a lid designed tobe locked onto the bowl so as to make it possible for the pressureinside the appliance to be increased, and for food to be cooked underpressure.

The present invention also relates to a method of cooking food underpressure in a closed vessel, in which method the pressure or thetemperature inside the vessel containing the food is increased.

PRIOR ART

It is already known that household pressure-cooking appliances of thepressure cooker type can be equipped with pintle or flap valve membersystems reacting to the pressure prevailing inside the appliance toclose the appliance in leaktight manner at or above a determinedpressure.

In general, such valve member systems are mounted in the lid of theappliance to move in a valve seat between low and high abutmentpositions. Once the lid has been locked onto the bowl, the valve membersystems go progressively from their low abutment positions to their highabutment positions, under the influence of the heating of the gaseousmedium present in the bowl at the beginning of cooking. Known systemsthus react to the progressive increase in pressure, and allow a smallquantity of an air/steam mixture to escape until the valve memberreaches its high abutment position.

Such systems enable a pressure cooker to operate acceptably, but theysuffer from a drawback related to the persistence of the presence of airin the gaseous cooking medium. The valve member reaches the highabutment position at a temperature or pressure value that is poorlycontrolled and imprecise, and in any event at a pressure or temperature(about 70° C.) that is low, giving rise to the valve member closingprematurely, so that the cooking medium still contains a non-negligiblefraction of air, which is prejudicial to the food being cooked well in acooking time optimized for the pressure/temperature relationship.

In addition, in known household pressure-cooking appliances, a pintlesystem reacting to pressure is also associated with an opening orimproper-closure safety device serving to allow the pressure inside thepressure cooker and thus inside the valve member system to increase onlyif the lid is correctly positioned and locked. It can thus be understoodthat, for safety reasons, valve member systems are designed to reachtheir high abutment positions at pressure values that are relativelylow, and in any event generally lower than 4 kilopascals (kPa), which isthe value commonly accepted for user-safe opening. Such devices preventthe escape of air that results from the beginning of cooking.

SUMMARY OF THE INVENTION

The objects assigned to the invention are thus to remedy the variousabove-mentioned drawbacks, and to provide a novel method and a novelappliance for household cooking under pressure, making it possible tobleed air from the appliance under pressure as fully as possible and incontrolled manner, but without preventing the pressure increase ortemperature increase stage from taking place properly, and in particularwithout lengthening the cooking time, or degrading the quality of thefood.

Another object of the invention is to provide a novel cooking appliancemaking it possible to bleed off the air as effectively as possiblebefore the cooking stage proper, while also offering safety of as high alevel as possible, enabling the appliance to lock as soon as lowpressure values are reached.

Another object of the invention is to provide a novel cooking appliancethat is of particularly simple and effective design and that does notinterfere with operation of other devices of the appliance, inparticular its safety devices.

Another object of the invention is to provide a novel cooking appliancein which the bleed system is easy to incorporate.

The objects assigned to the invention are achieved by means of ahousehold appliance for cooking under pressure, the appliance includinga cooking bowl and a lid designed to be locked onto the bowl so as tomake it possible for the pressure inside the appliance to be increased,the appliance being provided with bistable calibrated leakage meanssuitable for taking up firstly an open position in which the pressureinside the appliance is allowed to increase continuously to above adetermined pressure P₀, while also allowing air to be bled from theappliance, and secondly a closed position corresponding to an absence ofleakage of air to the outside, the open position being sustained for apredetermined time interval Δt after reaching P₀ or its correspondingtemperature value T₀, or until predetermined values are reached for thepressure or the temperature prevailing in the appliance, respectively P₁and T₁, where P₁>P₀, and T₁>T₀, the appliance being provided with atleast one closure/opening safety means, of the valve type, whoseposition is sensitive to the pressure prevailing in the bowl, and whichis mounted to move between two stable abutment positions, namely a firstposition in which the means puts the inside of the bowl intocommunication with the outside below the determined pressure P₀, and asecond position in which the means close off communication from the bowlto the outside when the pressure P₀ is reached, so as to allow thepressure inside the appliance to increase and so as to allow cooking totake place.

The objects assigned to the invention are also achieved by means of amethod of cooking food under pressure in a closed vessel, in whichmethod:

the pressure or the temperature inside the vessel containing the food isallowed to increase;

a step is performed in which air and steam are bled from the vesselwhile also allowing the pressure inside the vessel to increase, the steplasting for a time sufficient to ensure that substantially all of theair has been bled from the vessel, or until a predetermined pressure ortemperature is reached;

then bleeding is stopped by making the vessel fully leaktight; and

the food is cooked under pressure;

the method being characterized in that the pressure or temperatureinside the vessel containing the food is allowed to increase byappliance-opening safety means that are sensitive to pressure and thatclose the vessel as from a determined pressure, preferably less than orequal to 4 kPa, and the step in which air and steam are bled isperformed once the safety means have closed.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention appear in greater detailon reading the following description with reference to the accompanyingdrawings which are given by way of non-limiting illustrative example,and in which:

FIG. 1 is a fragmentary section view of a first embodiment of calibratedleakage means of the invention that react to temperature;

FIG. 2 is a fragmentary section view of a second embodiment ofcalibrated leakage means of the invention that react to pressure;

FIG. 3 is a fragmentary section view of a third embodiment of a systemof the invention that reacts to temperature and that is incorporated ina closure safety device;

FIG. 4 is a fragmentary section view of a fourth embodiment ofcalibrated leakage means of the invention that react to pressure andthat are incorporated in a closure safety device;

FIG. 5 is a fragmentary section view of a fifth embodiment of calibratedleakage means of the invention that react to pressure;

FIG. 6 is a fragmentary section view of a sixth embodiment of calibratedleakage means of the invention that react to temperature and that areincorporated in a valve ramp;

FIG. 7 is a fragmentary section view of a seventh embodiment ofcalibrated leakage means of the invention, corresponding to theembodiment shown in FIG. 5, but incorporated in a closure safety device;

FIG. 8 is a partially exploded perspective view of an eighth embodimentof a bleed system of the invention that reacts to time; and

FIGS. 9A and 9B are fragmentary section views showing another embodimentof a bleed system of the invention that reacts to temperature.

DETAIL DESCRIPTION

In the following examples, the air bleed systems or calibrated leakagemeans of the invention are incorporated or mounted in a householdappliance for cooking under pressure, of the pressure cooker type,comprising in a manner known per Se a cooking bowl (not shown in thefigures) and a lid 2 serving to be locked onto or fitted to the bowl byany suitable means, so as make it possible for the pressure inside theappliance to be increased, and for food to undergo cooking proper. Theair bleed systems of the invention are designed to be incorporated inand fitted in any type of pressure cooker, independently of the systemfor locking the lid to the bowl, regardless of whether it is a lockingsystem that uses a locking bar, ramps on the bowl and on the lid, jawsmounted to move radially, or any other system. The householdpressure-cooking appliances concerned by the invention are thuslocking-bar pressure cookers, bayonet-fitting pressure cookers,radial-jaw pressure cookers, or “manhole” pressure cookers, this listnaturally being given merely by way of non-limiting illustration.

In the invention, the cooking appliance is provided with calibratedleakage means enabling preferably all of the air to be bled from thepressure cooker before the appliance is regulated at its normal pressureor before the pressure level is sustained at a constant level (inpressure cookers having a visual pressure indicator), corresponding tothe cooking stage proper. In the invention, the calibrated leakage meansmay be of a plurality of types, corresponding to various modes oftriggering. Thus, the trigger parameter may be the temperature reachedby the gaseous medium, the pressure of said gaseous medium or else atime interval that is predetermined, thus corresponding substantially toan estimated reference temperature or pressure.

The general principle of the invention is based on implementingcalibrated leakage means or a calibrated leakage system that allows airto escape until a given temperature or pressure is reached, whilesimultaneously enabling the pressure inside the appliance to increase soas to obtain an overall cooking time that is short.

Thus, the household pressure-cooking appliance of the invention isprovided with bistable calibrated leakage means suitable for taking upfirstly an open position in which the pressure inside the appliance canincrease continuously to above a determined pressure P₀, while allowingair to be bled from the appliance, and secondly a closed positioncorresponding to an absence of air leakage to the outside, the openposition being sustained for a predetermined time interval Δt afterreaching P₀ or its corresponding temperature value T₀, or untilpredetermined values are reached for the pressure or the temperatureprevailing in the appliance, respectively P₁ and T₁, where P₁>P₀, andT₁>T₀.

Thus, in a first variant embodiment, as shown in FIG. 1, the calibratedleakage means may be sensitive to temperature and may be formed by abimetallic piece 3 that is, for example, disk-shaped, and that isincorporated in a chamber 4 defined between two parts mounted one on theother, e.g. by interfitting, screw-fastening, or crimping in particular,and formed by a top body 9A and a bottom body 9B mounted one in theother in a hole through the lid 2. The top body 9A is in communicationwith the outside of the pressure cooker, and thus with atmosphericpressure, via a calibrated opening 6 of any shape, e.g. circular oroval. The bottom body 9B is in communication with the inside of thepressure cooker via an internal orifice 5 of any shape and, for examplein axial alignment with the calibrated opening 6.

Advantageously, as shown in FIG. 1, the bimetallic disk 3 may be held inposition via its periphery by means of spaced-apart crenellations 4Aintegral with the top body 9A, the total through section between thecrenellations naturally being greater than the section of the calibratedopening 6, so that air and steam coming from inside the pressure cookerand escaping via the calibrated opening 6 can pass through freely. AnO-ring gasket 7 is positioned in a recess in the top body 9A to surroundthe calibrated opening 6 and to serve as a leaktight support for thebimetallic disk 3 when it takes up its high, closed position, as shownin the left portion of FIG. 1.

Thus, in its position shown in the right half of FIG. 1, the bimetallicdisk 3 is held in the open position, so that, at the beginning ofcooking, it allows air to pass from the pressure cooker via itsperiphery and between the crenellations, the air then escaping throughthe calibrated opening 6. In its position shown in the left portion ofFIG. 1, the bimetallic disk 3 has changed shape due to the increase inthe temperature inside the pressure cooker, and thus comes intoleaktight abutment against the O-ring gasket 7, thereby itself directlyclosing the calibrated opening 6 at a characteristic temperature T₁ thatis characteristic of the bimetallic disk 3 and that corresponds to itscomponent materials deforming.

As is well known to the person skilled in the art, the deformationcharacteristics of bimetallic pieces are reversible, and, when thetemperature falls again at the end of cooking, the bimetallic disk 3returns to its initial open position corresponding to the left portionof FIG. 1.

Thus, in the invention, the air leakage allowed by the calibratedopening 6 is sufficiently small and controlled to enable the pressureinside the pressure cooker to rise normally and without disturbance,while enabling said calibrated opening 6 to allow air to escape untilthe closure temperature of the device is reached, which closuretemperature is not less than 100° C.±2° C., or preferably equal to 102°C.±2° C., it being possible for the closure temperature to be as high asabout 104° C. After closure, the optimum food cooking temperature isreached, and is approximately in the range 105° C. to 120° C.

Advantageously, in order to satisfy the above-mentioned closuretemperature conditions, the calibrated leakage means of the inventioncomprise at least one calibrated opening 6 allowing leakage equivalentto an opening of section lying in the range 1.75 square millimeters(mm²) to 4.15 mm², and preferably about 2.80 mm², and a closure element(the bimetallic disk 3, in this example) which is mounted to move and ismounted in association with said at least one calibrated opening 6.

Various variable parameters have been taken into account for determiningthe limits of this preferred calibrated leakage section, while bearingin mind that the aim is to guarantee:

effective air bleeding while departing little from the ideal steampressure/temperature curve; and

reliability for the device that must act in spite of these variousparameters and in spite of the inevitable dispersions related to thetest conditions and to the component parts of the device.

The parameters having an influence taken into account were: bleed time,operating pressure, heating power, level to which the pressure cooker isfilled, and mean temperature of the steam.

By way of a variant embodiment (not shown in the figures), instead ofthe bimetallic disks, the means reacting to the temperature prevailinginside the appliance may comprise a wax actuator or a solenoid valveassociated with a temperature sensor or with any equivalent means. Byway of an additional variant, as shown in FIG. 2, the calibrated airleakage means may comprise a heavy valve pintle 10 mounted to slidefreely in a bore in the lid 2 between two abutment positions. When thepintle 10 is in the position shown in the left portion of FIG. 2, therespective dimensions and shapes of the bore and of the pintle 10 aresuch that a calibrated orifice 6 is provided peripherally between thepintle 10 and the lid 2, allowing air or steam to escape until apredetermined pressure value P₁ is reached. Conversely, since the bottomportion of the pintle 10 is provided with an O-ring gasket 7 supportedby a collar, then when the predetermined pressure P₁ is reached, thepintle 10 reaches its high position shown in the right portion of FIG.2, with the O-ring gasket 7 then coming to close the calibrated opening6 in leaktight manner.

Thus, in the invention, the bistable calibrated leakage means are formedby associating a calibrated opening 6 with means sensitive totemperature or to pressure, or else with means making it possible tocount down a time interval and closing or releasing said calibratedopening 6.

By way of an additional variant, as shown in FIGS. 9A and 9B, thebimetallic disk 3 may be associated with a heavy valve pintle 80provided at one end with a spike 81 designed to come into engagementwith a spike-receiving seat formed by the top portion 82 of a throughhollow tubular body 83 fitted by any known means to the lid 2 andputting the inside of the pressure cooker into communication with theoutside via the orifice 5. In this variant, the bimetallic disk 3 issecured to the inside of a top body 85 forming a cap and designed to fitover the tubular body 83 so as to come, in a rest position, intoabutment against studs 86 defining a crenellated collar that projectsradially from said tubular body 83. In this embodiment, the bimetallicdisk 3, which extends transversely inside the top body 85, is providedwith a central hole in which the heavy valve pintle 80 is mountedaxially and fixed, the heavy valve pintle also projecting axially fromthe top body 85 via a bore in which it slides freely, so that, at thebeginning of cooking (FIG. 9A), the calibrated orifice 6 defined betweenthe periphery of the spike 81 and the top portion 82 is open, thuscorresponding to an open or bleed position in which the calibratedleakage means allow air to escape. Once the temperature corresponding tothe bimetallic disk 3 changing shape has been reached (FIG. 9B), thebimetallic disk 3 changing shape enables the top body 85 to move axiallyupwards, and enables the spike 81 to move in the opposite direction andto come to close off the calibrated opening 6 by resting in leaktightmanner against the top end 82.

In this variant, the bimetallic disk 3 and the heavy valve pintle 80 maybe pre-mounted in or on the top body 85 so as to form a single accessorywhich is easier for the user to put in place on the main body 83. Inthis variant embodiment, the calibrated air leakage means thus include aheavy valve pintle 80 supported by a bimetallic disk 3, itself supportedby the main body 3 which is designed to be mounted facing the opening 5in the lid 2, so that the calibrated opening 6 is defined between saidheavy valve pintle 80 and the opening 5 forming the seat for receivingthe pintle in leaktight manner when the bimetallic disk 3 is in theclosed position (FIG. 9B), corresponding to the bleed being closed andto temperature conditions T₁. In this variant, the opening 5 thusunderlies a tubular body 83 whose top portion 82 forms the seat forreceiving the heavy valve pintle 80, the main body 85 being formed by aremovable cap designed to fit over said tubular body 83.

By way of an additional variant, the calibrated opening 6 may also beformed by the opening(s) defined by the studs 86 of the crenellatedcollar (FIG. 9A). In this variant, the technical means implemented areidentical to the preceding variant, but they are organized significantlydifferently. Thus, the calibrated air leakage means comprises a heavyvalve pintle 80 supported by a bimetallic disk 3, itself supported by atubular body 83 serving to be mounted facing an opening 5 in the lid 2,said opening 5 forming the seat for receiving the pintle 80 in leaktightmanner when the bimetallic disk 3 is in the closed position, thecalibrated opening 6 being formed by openings defined in a crenellatedcollar forming an abutment for the tubular body 83 when the bleed isopen.

Advantageously, the cooking appliance of the invention may also beprovided with pressure cooker closure/opening safety means of the safetyvalve type, having a valve member mounted to move between two stableabutment positions, with its position being sensitive to the pressureprevailing in the bowl. In the first stable abutment position, thesafety means put the inside of the bowl into communication with theoutside when the pressure is below the determined pressure P₀, and inthe second stable abutment position, the safety means close offcommunication between the bowl and the outside when the pressure P₀ isreached, so that the pressure inside the appliance can be increased andso that cooking can take place. Such opening/closure safety means arewell known to the person skilled in the art, and they make it possibleto ensure that the lid is indeed in the stable locked position on thebowl, it being possible for the valve member to move under pressure onlyif the stable locked position is indeed reached. This prevents thepressure from increasing while the lid is improperly locked. Conversely,such closure/opening safety means prevent the appliance from beingopened in untimely manner while residual pressure remains in theappliance, because only the low position of the safety valve membermakes it possible for the appliance to be opened.

By associating the bistable calibrated leakage means of the inventionwith closure/opening safety means, it is possible to obtain a pressurecooker which is very safe, and in which the safety system is triggeredearly, thereby procuring good user safety while still enabling the airto be bled effectively from the appliance, by means of the existence ofa calibrated leak that does not interfere with the rising of the valvemember of the closure safety means.

In particularly advantageous variant embodiments, the appliance of theinvention is provided with calibrated leakage means which areincorporated in the safety device itself. The variants of the inventionthat correspond to this configuration are shown in FIGS. 3, 4, and 7.

In the preferred variants of the invention shown in FIGS. 3, 4, and 7,the bistable calibrated leakage means are incorporated or supported inan Aroma pintle 15 which constitutes pressure cooker closure safetymeans in the meaning of the invention. The Aroma pintle 15, which is ofthe pressure-gauge rod type, serves to perform the opening and closurelocking function for locking the lid 2 onto the bowl as soon as aminimum pressure, e.g. about 4 kPa, is reached inside the pressurecooker. As soon as the minimum pressure value is reached, the Aromapintle 15 rises from its low abutment position (shown in FIG. 3) toreach its high abutment position in which the pressure cooker ispressure-tight. In the high abutment position, the Aroma pintle 15 comesto engage in a corresponding hole provided in a fixed member of thepressure cooker, e.g. secured to a bowl handle, so that opening orclosure of the pressure cooker is prevented. Since such safety means arewell known to the person skilled in the art, they are not described inany further detail below.

The variant shown in FIG. 3 includes a bimetallic disk 3 mounted in achamber 4 provided between the bottom portion of the body 16 of theAroma pintle 15 and a separate part 17 mounted on the bottom portion.The chamber 4 is in fluid communication with the outside and with theinside of the pressure cooker respectively via a through channel 18provided through the body 16, and via an opening 5 provided through theseparate part 17 and preferably in axial alignment with the channel 18.The bimetallic disk 3 is held and supported elastically at least in partby an O-ring gasket 7 in the chamber 4, and as shown in the righthalf-portion of FIG. 3, the bimetallic disk closes off the calibratedopening 6 as soon as the determined minimum temperature value T₁ isreached inside the pressure cooker. The left half-portion of FIG. 3shows the bimetallic disk 3 in the position in which it opens thecalibrated opening 6, corresponding to the bimetallic disk 3 deforming,its deformation being associated with a temperature value that is lowerthan the predetermined temperature T₁. In this open position, air can bebled from the pressure cooker via the orifice 5 and via the channel 18through the calibrated opening 6, although the Aroma pintle 15 occupiesits sealing high position, the annular O-ring gasket 19 being inleaktight elastic abutment against the bottom face of the lid 2. In thisposition, the pressure inside the pressure cooker increases from thebeginning of cooking, while simultaneously allowing the air/steammixture to be bled. In this variant, the calibrated air leakage meansare incorporated in the Aroma pintle 15, and, by way of a moving closureelement, they comprises a bimetallic disk supported by said Aroma pintle15.

The variant embodiment shown in FIG. 4 is an embodiment in which thebleed system of the invention reacts to pressure. In this variant, thecalibrated leakage means are incorporated in a first Aroma pintle 15 andare formed by a second Aroma pintle 15A that is concentric with saidfirst Aroma pintle 15 (by being disposed outside or preferably insidesaid first Aroma pintle), and mounted to move axially relative thereto.This variant thus corresponds to a double Aroma pintle 15A in which thefirst Aroma pintle 15 makes the appliance pressure-tight as soon as afirst pressure level, e.g. about 4 kPa, is reached, by coming to closethe outlet orifice 21 provided between the outside periphery of the body16 and the inside periphery 16A of the second Aroma pintle 15A. Thesecond Aroma pintle 15A is of weight and dimensions such that, when thefirst Aroma pintle 15 is in this high abutment position, said secondAroma pintle opens the calibrated opening 6 provided between the outsideperiphery of the body 16A and a bore in the pressure cooker, the boreadvantageously being situated in the lid 2. In this position, althoughthe pressure inside the pressure cooker increases, bleeding can takeplace before the final cooking pressure is reached. As soon as the finaloperating pressure is reached, the second Aroma pintle 15A takes up itshigh, abutment position in which the O-ring gasket 7 closes off thecalibrated opening 6 in elastic and leaktight manner.

The variant embodiment shown in FIG. 5 shows calibrated leakage meansformed of a deformable gasket 30 that can be deformed under drive fromthe pressure to come to close off at least one calibrated opening 6, andpreferably a plurality of calibrated openings 6. In this variant, thedeformable gasket 30 is incorporated in a bore in the pressure cooker,and, for example, in the lid 2, and it comprises a deformable diaphragm31 which is connected, e.g. by interfitting, via one of its ends 32 tothe edge of the bore, and which defines, in the vicinity of its otherend 33, a central well 34 through the wall of which at least onecalibrated hole 6 is provided. This configuration defines a sort ofconvex collar whose central zone is folded inwards and is open to formthe central well 34. The central well 34 is terminated by a sealing face35 forming a sealing collar that serves to press against the body of thegasket formed by the bottom face of the end 32, as from a predeterminedpressure value that is not less than a reference value P₁. The lefthalf-portion of FIG. 5 shows the sealing position of the deformablediaphragm 30, which position is reached as from a predetermined pressurevalue P₁, while the right half-portion of FIG. 5 shows the open positionof said deformable diaphragm 30. In said open position, air can be bledfrom the pressure cooker even though its pressure increasessimultaneously in conventional manner.

FIG. 7 shows a variant using the configuration of a deformable gasket 30as shown in FIG. 5. In this variant embodiment, the deformable gasket 30incorporates a conventional Aroma pintle 15 which is mounted to slidefreely in the central well 34 between two stable abutment positions. Asshown, the sealing face 35 is provided with a hole 40 in which the Aromapintle 15 is mounted to slide freely, the two sides of the sealing face15 around the hole 40 forming a sealing seat for the two abutmentpositions of the Aroma pintle 15. A bleed system of the invention isthus obtained associated with pressure cooker closure/opening safetymeans.

The variant embodiment shown in FIG. 6 shows a bleed system of theinvention that is incorporated in a ramp 50 of a valve member 51. Thevalve member ramp 50 is mounted to be urged resiliently into a returnposition against the neck 52 of a valve member 53 by means of a helicalspring 54 interposed in a recess 55 in the ramp 50 between said ramp 50and the lid 2. A bimetallic disk 3 is interposed between the neck 52 andthe head 56 of the ramp 50. When the bimetallic disk 3 is in the openposition, a leg 57 of the ramp 50, which leg is situated in the bottomportion thereof, opens a calibrated opening 6 provided through the lid2, thereby making it possible for bleeding to take place. When thetemperature in the cooking vessel reaches the threshold for triggeringthe bimetallic disk 3, said bimetallic disk snaps over and enables thecalibrated opening 6 to be closed off by the leg 57, by means of theramp 50 moving axially against the resilient force exerted by thehelical spring 54. In this position, the bleed system is sealed off, thecalibrated leakage means of the invention then including a bimetallicdisk 3 mounted in resilient abutment against the ramp 50 of the valvemember 51, the ramp being mounted to move relative to the calibratedopening 6, so that the ramp comes to open or to close said calibratedopening 6 depending on the position of the bimetallic disk 3.

The variant embodiment shown in FIG. 8 shows a householdpressure-cooking appliance of the invention, having bistable calibratedleakage means allowing air to be bled from the appliance, the bleedingbeing sustained for a predetermined time interval □t after a determinedpressure valve P₀ or its corresponding temperature value T₀ is reached.

In this variant, the appliance is equipped with a timer 60 ofconventional type having means for counting down the predetermined time□t from the instant at which the reference pressure or temperature P₀ orT₀ is reached, and a system 61 for opening and closing a calibratedopening 6. The system 61 also incorporates a pressure or temperaturesensor for sensing when the pressure P₀ or the temperature T₀ isreached. This assembly forms calibrated leakage means 60 preferablyincorporated in the lid 2 of the pressure cooker. At the beginning ofcooking, the timer counts down the predetermined time □t enabling all ofthe air to be bled from the pressure cooker via the calibrated hole 6.Once the predetermined time □t has elapsed, the opening and closuresystem 61 closes the calibrated hole 6. At the end of cooking, thepressure or temperature sensor incorporated in the timer can sense thedrop in pressure or in temperature and thus allow the calibrated airleakage means of the invention to be opened again.

In all of the above-mentioned examples, the calibrated leakage means arepresented as being preferably incorporated in or fitted to the lid 2 ofthe pressure cooker. In the meaning of the invention, it is howeverpossible to incorporate such calibrated leakage means in other portionsof the pressure cooker, and in particular in the bowl or in the meansfor taking hold of the pressure cooker, without going beyond the ambitof the invention.

Similarly, the preceding examples present a cooking appliance whosecalibrated leakage means allow air to be bled from the appliance as afunction of the movement of a movably mounted closure element. In themeaning of the invention, such an element may be controlled by any meanswell known to the person skilled in the art, and in particular by wavesof the radio or electromagnetic wave type.

The invention also relates to a method of cooking food under steampressure in a closed vessel, in which method the pressure or thetemperature inside the vessel containing the food is allowed toincrease. Advantageously, the pressure or temperature inside the vesselis allowed to increase by pressure cooker opening or closure safetymeans, which means are sensitive to pressure and close the vessel asfrom a determined pressure that is preferably equal to 4 kPa. In theinvention, the method is characterized in that:

a step is performed in which air and steam are bled from the vesselwhile also allowing the pressure inside the vessel to increase, the steplasting for a time sufficient to ensure that substantially all of theair has been bled from the vessel, or until a predetermined pressure ortemperature is reached;

then bleeding is stopped by making the vessel fully leaktight; and

the food is cooked under pressure.

Advantageously, the pressure or temperature inside the vessel containingthe food is allowed to increase by appliance-opening safety means thatare sensitive to pressure and that close the vessel as from a determinedpressure, preferably less than or equal to 4 kPa, and the step in whichair and steam are bled is performed once the safety means have closed.

Preferably, the method of the invention makes it possible to bleed airso that the food is cooked under a steam-only atmosphere.

Preferably, the bleeding step is performed until an average vesseltemperature of approximately at least 96° C. is reached, or until a meanpressure of approximately at least 150 millibars is reached.

Preferably, the bleeding step thus takes place within a temperaturerange from 96° C. to 104° C., and even more preferably from 96° C. to102° C.

The bleed system of the invention makes it possible to reduce the totalcooking time significantly, and to allow the temperature of the food tobe increased more quickly, thereby enabling its vitamins to be retainedbetter because of the absence of an air/steam mixture in the cookingvessel. The system of the invention also makes it possible to satisfythe general relationships defining the increase in the temperature ofwater under pressure, and to limit the loss of vitamins and of mineralsalts from the food.

In addition, bleeding off the air makes it possible to avoid oxidationof the food, which is a guarantee of cooking quality.

SUSCEPTIBILITY OF INDUSTRIAL APPLICATION

The invention can be applied industrially to manufacturing and designinghousehold appliances for cooking food, in particular householdappliances for cooking food under pressure, of the pressure cooker type.

1. A household appliance for cooking under pressure, the appliancecomprising a cooking bowl and a lid designed to be locked onto the bowlso as to make it possible for the pressure inside the appliance to beincreased, said appliance being provided with at least one calibratedopening and bistable calibrated air leakage means arranged andconfigured to be positionable between an open position in which thepressure inside the appliance is allowed to increase continuously toabove a determined pressure P₀, while also allowing air to be bled fromthe appliance through said opening, and a closed position correspondingto an absence of leakage of air to the outside, said open position beingsustained for at least one of a predetermined time interval Δt afterreaching a pressure value P₀, the predetermined time interval Δt afterreaching a temperature value T₀ corresponding to the pressure value P₀,until a predetermined pressure value P₁ is reached, and until apredetermined temperature value T₁ is reached, where P₁>P₀, and T₁>T₀,said appliance being provided with a closure/opening safety means whoseposition is sensitive to the pressure prevailing in the bowl, and whichis mounted to move between two stable abutment positions, namely a firstposition in which said closure/opening safety means puts the inside ofthe bowl into communication with the outside below the determinedpressure P₀, and a second position in which said closure/opening safetymeans prevent opening of the appliance and close off communication fromthe bowl to the outside when the pressure P₀ is reached, so as to allowthe pressure inside the appliance to increase and so as to allow cookingto take place.
 2. The appliance of claim 1, wherein said calibrated airleakage means further comprises said at least one calibrated opening (6)configured for leakage to take place that is equivalent to an opening of1.75 mm² to 4.15 mm², and preferably about 2.80 mm², and a movablymounted closure element associated with said at least one calibratedopening.
 3. The appliance of claim 1, wherein the calibrated air leakagemeans is configured to react to the temperature prevailing in theappliance.
 4. The appliance of claim 3, wherein the calibrated airleakage means further comprises one of a bimetallic disk, a waxactuator, and a solenoid valve associated with a temperature sensor. 5.The appliance of claim 4, wherein the calibrated air leakage meansfurther comprises a heavy valve pintle supported by a bimetallic disk,the bimetallic disk being supported by a main body mounted facing anopening in the lid, so that the calibrated opening is defined betweensaid pintle and the opening forming a seat for receiving the pintle inleaktight manner when the bimetallic disk is in the closed position. 6.The appliance of claim 5, wherein the opening underlies a tubular body,a top portion of which forms the seat for receiving the pintle, the mainbody being formed by a removable cap fitting over said tubular body. 7.The appliance of claim 4, wherein the calibrated air leakage meansfurther comprises a heavy valve pintle supported by a bimetallic disk,the bimetallic disk being supported by a tubular body mounted facing anopening in the lid, said opening forming a seat for receiving the pintlein leaktight manner when the bimetallic disk is in the closed position,the calibrated opening being formed by openings defined in a crenellatedcollar forming an abutment for the tubular body.
 8. The appliance ofclaim 1, wherein the calibrated air leakage means is configured to reactto the pressure prevailing in the appliance.
 9. The appliance of claim1, wherein the calibrated air leakage means are incorporated in theclosure/opening safety means.
 10. The appliance of claim 9, wherein thecalibrated air leakage means are incorporated in an Aroma pintle and, byway of a moving closure element, are provided with a bimetallic disksupported by the Aroma pintle.
 11. The appliance of claim 10, whereinthe calibrated leakage means are incorporated in a first Aroma pintleand are formed by a second Aroma pintle that is concentric with thefirst Aroma pintle, and that is mounted to move relative to the firstAroma pintle.
 12. The appliance of claim 8, wherein the calibrated airleakage means are formed by a deformable gasket element that isconfigured to be deformed by the pressure and close off the calibratedhole.
 13. The appliance of claim 12, wherein the deformable gasket isincorporated in a bore in the lid of the appliance, and has a deformablediaphragm with a central well in which at least one calibrated hole isprovided, said central well being terminated by a sealing faceconfigured to press against the body of the gasket to form a sealingseat from a pressure at least equal to P₁.
 14. The appliance of claim13, wherein an Aroma pintle is mounted in the central well to slidefreely between two abutment positions.
 15. The appliance of claim 3wherein the calibrated air leakage means are incorporated in a ramp of asafety valve member.
 16. The appliance of claim 15, wherein thecalibrated air leakage means further comprises a bimetallic disk mountedin resilient abutment against the ramp of the valve member, the rampbeing mounted to move relative to the calibrated hole so that the rampcomes to open or to close the calibrated hole depending on the positionof the bimetallic disk.
 17. The appliance of claim 1, wherein thecalibrated air leakage means further comprises at least one of atemperature sensor and a pressure sensor for sensing when thetemperature T₀ and the pressure P₀ is reached, respectively, and a timerfor counting down the predetermined time Δt as from the instant at whichP₀ or T₀ is reached, and an opening and closure system for opening andclosing the calibrated hole.
 18. The appliance of claim 1, wherein thecalibrated air leakage means are organized on the lid of the cookingappliance.